急性胰腺炎时，最有诊断意义的血清酶是 ( )

A．氨基转移酶

B．碱性磷酸酶

C．肌酸激酶

D．淀粉酶

E．酸性磷酸酶

________ he found the idea interesting, it was too difficult to be of practical use.

A．While

B．Once

C．If

D．Until